API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Mar 12, 2021 Callisto / (Jupiter) 504 SATELLITE PHYSICAL PROPERTIES: Mean radius (km) = 2410.3 +- 1.5 Density (g cm^-3)= 1.834 +- 0.004 GM (km^3/s^2) = 7179.2834 +- 0.0097 Geometric Albedo = 0.17 +- 0.02 SATELLITE ORBIT (at J2000.0 epoch, 2000-Jan-1.5): Semi-major axis, a (km)~ 1,883,000 Orbital period ~ 16.691 d Eccentricity, e ~ 0.00744 Rotational period= Synchronous Inclination, i (deg) ~ 0.200 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Thu Aug 14 16:19:34 2025 Pasadena, USA / Horizons ******************************************************************************* Target body name: Callisto (504) {source: jup365_merged} Center body name: Sun (10) {source: jup365_merged} Center-site name: BODY CENTER ******************************************************************************* Start time : A.D. 2025-Jan-01 00:00:00.0000 TDB Stop time : A.D. 2025-Jan-01 00:01:00.0000 TDB Step-size : 1 minutes ******************************************************************************* Center geodetic : 0.0, 0.0, 0.0 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 0.0, 0.0, 0.0 {E-lon(deg),Dxy(km),Dz(km)} Center radii : 695700.0, 695700.0, 695700.0 km {Equator_a, b, pole_c} Output units : AU-D Calendar mode : Mixed Julian/Gregorian Output type : GEOMETRIC cartesian states Output format : 2 (position and velocity) Reference frame : Ecliptic of J2000.0 ******************************************************************************* JDTDB X Y Z VX VY VZ ******************************************************************************* $$SOE 2460676.500000000 = A.D. 2025-Jan-01 00:00:00.0000 TDB X = 1.046927187861326E+00 Y = 4.980213520221207E+00 Z =-4.412635447845523E-02 VX=-1.076662893789138E-02 VY=-1.453153071657253E-03 VZ= 9.400054299331563E-06 2460676.500694444 = A.D. 2025-Jan-01 00:01:00.0000 TDB X = 1.046919711342476E+00 Y = 4.980212510788754E+00 Z =-4.412634795573506E-02 VX=-1.076574531183088E-02 VY=-1.454012353275114E-03 VZ= 9.385381807833990E-06 $$EOE ******************************************************************************* TIME Barycentric Dynamical Time ("TDB" or T_eph) output was requested. This continuous coordinate time is equivalent to the relativistic proper time of a clock at rest in a reference frame co-moving with the solar system barycenter but outside the system's gravity well. It is the independent variable in the solar system relativistic equations of motion. TDB runs at a uniform rate of one SI second per second and is independent of irregularities in Earth's rotation. CALENDAR SYSTEM Mixed calendar mode was active such that calendar dates after AD 1582-Oct-15 (if any) are in the modern Gregorian system. Dates prior to 1582-Oct-5 (if any) are in the Julian calendar system, which is automatically extended for dates prior to its adoption on 45-Jan-1 BC. The Julian calendar is useful for matching historical dates. The Gregorian calendar more accurately corresponds to the Earth's orbital motion and seasons. A "Gregorian-only" calendar mode is available if such physical events are the primary interest. REFERENCE FRAME AND COORDINATES Ecliptic at the standard reference epoch Reference epoch: J2000.0 X-Y plane: adopted Earth orbital plane at the reference epoch Note: IAU76 obliquity of 84381.448 arcseconds wrt ICRF X-Y plane X-axis : ICRF Z-axis : perpendicular to the X-Y plane in the directional (+ or -) sense of Earth's north pole at the reference epoch. Symbol meaning [1 au= 149597870.700 km, 1 day= 86400.0 s]: JDTDB Julian Day Number, Barycentric Dynamical Time X X-component of position vector (au) Y Y-component of position vector (au) Z Z-component of position vector (au) VX X-component of velocity vector (au/day) VY Y-component of velocity vector (au/day) VZ Z-component of velocity vector (au/day) ABERRATIONS AND CORRECTIONS Geometric state vectors have NO corrections or aberrations applied. Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA General site: https://ssd.jpl.nasa.gov/ Mailing list: https://ssd.jpl.nasa.gov/email_list.html System news : https://ssd.jpl.nasa.gov/horizons/news.html User Guide : https://ssd.jpl.nasa.gov/horizons/manual.html Connect : browser https://ssd.jpl.nasa.gov/horizons/app.html#/x API https://ssd-api.jpl.nasa.gov/doc/horizons.html command-line telnet ssd.jpl.nasa.gov 6775 e-mail/batch https://ssd.jpl.nasa.gov/ftp/ssd/horizons_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov *******************************************************************************